Micro optical fiber sensor device

ABSTRACT

A sensor device for measuring a concentration of a substance within a sample comprises a sensor comprising an optical fiber portion having a first end and a second end, the second end having a tip portion attached thereto and an active material incorporated within the tip portion, the tip portion adapted to be inserted into a sample, the active material capable of interacting with a substance within a sample, a light source coupled to the first end of the sensor for emitting a beam of light into and through the sensor and into a sample, the emitted beam of light having a wavelength and the active material interacting with a substance within a sample to change the wavelength of the emitted beam of light to produce a reflected beam of light and the sensor for transmitting the reflected beam of light out of the second end thereof, an optical detector for receiving the reflected beam of light from the second end of the sensor for producing a signal indicative of the reflected beam of light, and a processor for receiving the signal indicative of the reflected beam of light and for processing the signal to determine the concentration of a substance within a sample.

BACKGROUND OF THE INVENTION

This invention relates generally to a sensor device and moreparticularly to a micro optical fiber sensor device which may beemployed in a variety of sensor applications to monitor, sense, ormeasure a concentration of a material within a sample.

There are numerous applications in which a device is used to monitor ordetect a concentration of material within a substance. For example, itmay be required to know the concentration of a chemical in a sample ofmaterial such as knowing the concentration of sodium, calcium, or someother chemical composition in a sample. Monitoring or detecting aconcentration of a substance typically requires a set up of relativelycomplex, sensitive, and expensive equipment or instrumentation.Sometimes space requirements make it difficult to use the set up ofcomplex equipment and it would be advantageous to have equipment whichhas small dimensions and is easily transportable. Additionally, suchcomplex equipment may not provide results which are of a highresolution.

One known and important application for monitoring a concentration of amaterial within a sample deals with checking blood glucose fordiabetics. There are at least two known techniques for monitoring bloodglucose levels in humans. The two techniques are invasive which involvesextracting samples with the use of needles or syringes and noninvasive.Typically, for the invasive method, a patient employs a small lancetdevice which is used to prick or puncture a finger. Blood is thencollected onto a strip which has incorporated therein a chemicalreagent. The strip is then placed inside of a device that opticallyreads the chemical reaction of the blood on the strip and converts thisto a blood glucose level. It has been found very important to controlglucose levels in diabetics to reduce any complications associated withdiabetes. Many samples or finger pricks may be required to be taken foranalysis during the course of a day. Self monitoring of blood glucose bya patient is therefor very important in the treatment of diabetes. Sincefinger pricking or lancing is required for self monitoring levels ofglucose in a patient, many patients avoid this because it is painful andinconvenient. Therefore, a less invasive procedure would be desirable.The other methods, which have been termed noninvasive, typically involvea devices which uses near infrared light to detect blood glucose levels.These devices measure a glucose concentration in blood or an organism'stissue by use of an optical device without the need to collect blood orfracturing a part of the organism's tissue. Although these devices usenoninvasive methods, in that no blood is collected, none of thesedevices have been commercially accepted or viable.

The present invention is designed to obviate and overcome many of thedisadvantages and shortcomings associated with the prior use of complextesting and monitoring equipment. Additionally, the present invention issimple to use, provides extremely quick results and high resolution, andis easily transportable. The present invention uses relativelyinexpensive components which results in a commercially viable product.Further, the micro optical fiber sensor device of the present inventionis relatively noninvasive since it does not require the drawing of bloodand provides immediate results which does not require related bloodprocessing such as centrifugation, storage, transportation, and othertime consuming testing.

SUMMARY OF THE INVENTION

The present invention is a sensor device for measuring a concentrationof a substance within a sample which comprises a sensor comprising anoptical fiber portion having a first end and a second end, the secondend having a tip portion attached thereto and an active materialincorporated within the tip portion, the tip portion adapted to beinserted into a sample, the active material capable of interacting witha substance within a sample, a light source coupled to the first end ofthe sensor for emitting a beam of light into and through the sensor andinto a sample, the emitted beam of light having a wavelength and theactive material interacting with a substance within a sample to changethe wavelength of the emitted beam of light to produce a reflected beamof light and the sensor for transmitting the reflected beam of light outof the second end thereof, means for receiving the reflected beam oflight from the second end of the sensor for producing a signalindicative of the reflected beam of light, and a processor for receivingthe signal indicative of the reflected beam of light and for processingthe signal to determine the concentration of a substance within asample.

Another example of the present invention is a sensor device formeasuring a concentration of a substance within a sample which comprisesa sensor comprising an optical fiber portion having a first end and asecond end, the second end having a tip portion attached thereto and anactive material incorporated within the tip portion, the tip portionadapted to be inserted into a sample, the active material capable ofinteracting with a substance within a sample, a light source foremitting a beam of light of a preselected wavelength with the lightsource being coupled to an optical device capable of transmitting thebeam of light therethrough, the transmitted beam of light being directedinto the first end of the sensor, through the sensor and out of thesecond end into a sample, the active material interacting with asubstance within a sample to change the wavelength of the transmittedbeam of light to produce a reflected beam of light and the sensor fortransmitting the reflected beam of light from the second end, throughthe sensor, and out of the first end thereof, the optical device beingfurther capable of reflecting the reflected beam of light, means forreceiving the reflected beam of light which is reflected by the opticaldevice for producing a signal indicative of the reflected beam of light;and a processor for receiving the signal indicative of the reflectedbeam of light and for processing the signal to determine theconcentration of a substance within a sample.

A further example of the present invention is a sensor device formeasuring a concentration of a substance within a sample which comprisesa sensor comprising an optical fiber portion having a first end and asecond end, the second end having a tip portion attached thereto and afirst and a second active material incorporated within the tip portion,the tip portion adapted to be inserted into a sample, the first activematerial capable of interacting with a first substance within a sampleand the second active material capable of interacting with a secondsubstance within a sample, a light source coupled to the first end ofthe sensor for emitting a beam of light into and through the sensor andinto a sample, the emitted beam of light having a wavelength and thefirst active material interacting with a first substance within a sampleto change the wavelength of the emitted beam of light to produce a firstreflected beam of light, the second active material interacting with asecond substance within a sample to change the wavelength of the emittedbeam of light to produce a second reflected beam of light, and thesensor for transmitting the first and second reflected beams of lightout of the second end thereof, means for receiving the first and secondreflected beams of light from the second end of the sensor for producinga first signal indicative of the first reflected beam of light and asecond signal indicative of the second reflected beam of light, and aprocessor for receiving the first and second signals and for processingthe first and second signals to determine the concentration of a firstsubstance within a sample and the concentration of a second substancewith a sample.

In light of the foregoing comments, it will be recognized that aprincipal object of the present invention is to provide an improvedsensor device which is hand held, portable, and easy to operate.

Another object of the present invention is to provide a sensor devicewhich has a tip portion of an extremely small size so that when it isinserted into a hand of a patient little or no sensation will beproduced or detected.

A further object of the present invention is to provide a sensor devicewhich is of simple construction and design and which can be easilyemployed with highly reliable results.

Another object of the present invention is to provide a sensor devicewhich is accurate and provides readings in a short time span.

A still further object of the present invention is to provide a sensordevice which is compact in design and is easily transportable forpersonal use.

These and other objects and advantages of the present invention willbecome apparent after considering the following detailed specificationin conjunction with the accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a micro optical fiber sensor deviceconstructed according to the present invention;

FIG. 2 is a block diagram of the micro optical fiber sensor deviceconstructed according to the present invention;

FIG. 3 is a perspective view of a tip portion of the micro optical fibersensor device shown in FIG. 1;

FIG. 4 is a schematic view of the micro optical fiber sensor device ofthe present invention being employed to sense a concentration in asample;

FIG. 5 is a block diagram of a second embodiment of the micro opticalfiber sensor device constructed according to the present invention;

FIG. 6 is perspective view of the sensor device of FIG. 5 illustratedmonitoring a concentration of glucose in a hand of a patient; and

FIG. 7 is a block diagram of a third embodiment of the micro opticalfiber sensor device constructed according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, wherein like numbers refer to like items,number 10 identifies a preferred embodiment of a micro optical fibersensor device constructed according to the present invention. Asillustrated in FIG. 1, the device 10 comprises a pencil or pen shapedbody 12 which includes a tip portion 14, a central body portion 16, andan end cap 18. The central body portion 16 further includes a displaydevice 20, such as an LED (light emitting diode) type display or an LCDtype display, for displaying information. The end cap 18, which may beremovable from the central body portion 16, is used to allow access intothe interior of the central body portion 16. Batteries (not shown) canbe inserted into the central body portion 16 to supply power to thedevice 10, as will be explained. The central body portion 16 may alsoinclude an ON/OFF switch 22 which may be used to operate the device 10.Other switches (not shown) may be incorporated into the central bodyportion 16 to further control the device 10. Additionally, the centralbody portion 16 houses electronic circuitry and other components whichwill be illustrated and explained in further detail herein. The device10 is sized and shaped to be a hand held type device which is portableand preferably is the size and shape of a pencil or a pen.

With reference now to FIG. 2, a block diagram of the circuitry andcomponents of the device 10 is shown. The device 10 includes a lightsource 30 which may be an LED, a laser, a laser diode, or otherexcitation source. The light source 30 is adapted to project a beam oflight 32 into a section fiber optic 34. The fiber optic 34 transmits abeam of light 36 to a tip portion or device 38 which is part of the tipportion 14. The beam of light 36 passes through the tip device 38 and areflected beam of light 40 can be reflected back from a sample (notshown) through the tip device 38 to a detector 42. The reflected beam oflight 40 typically has a wavelength or a frequency which is differentthan the wavelength or frequency of the beam of light 36. The detector42 is in turn connected to a computer 44 via an electrical connectionsuch as a wire 46. The detector 42 provides electrical signals over thewire 46 to the computer 44. The computer 44 may consists of, by way ofexamples, a microprocessor, a microcontroller, an ASIC chip, or anyother known equivalent device which is capable of processing electricalsignals. The computer 44 is further operatively connected to a powersupply 48, such as batteries, by a wire 50. The computer 44 may alsoconnected to the display device 20, the switch 22, and the light source30 although such connection is not illustrated in FIG. 2. Additionally,the computer 44 may also be connected to other switches (not shown)which may be provided with the device 10. In this manner, the additionalswitches are used to further control or operate other functions of thedevice 10.

The tip device 38 is shown in greater detail in FIG. 3 and is preferablya small device on the order of microns in diameter. The tip device 38may be constructed as is disclosed in U.S. Pat. Nos. 5,361,314 and5,627,922. In particular, the tip device 38 includes a non-tapered fiberoptic portion 60 and a tapered fiber optic portion 62 which is coatedwith an opaque material 64. The tip device 38 further includes a firstend 66 and a second end 68. The second end 68 further has a tip orportion 70 of material which is adhered thereto. The tip 70 ischemically treated which enables the tip 70 to interact with the sampleto be detected. Properties of the sensor or tip device 38 may varydependent upon the sample and the chemical or substance to be detectedby the device 10. As constructed, the tip device 38 allows for the beamof light 36 to pass through the first end 66, the second end 68, and thetip portion 70 and the reflected beam 40 is allowed to pass through thetip portion 70, the second end 68, and the first end 66.

As indicated above, the tip device 38 is extremely small on the order ofone-thousandth the width of a human hair and because of this size it canbe inserted through gaps in most cells or through the membrane of a cellwithout damaging the cell. The tip 70 may be bathed in chemical coatingsselected to react with biological compounds such as acid, calcium,oxygen, glucose, potassium, sodium, or any other material to bedetected. The beam of light 36 which is transmitted through the tipdevice 38 glows with its brightness and color varying according to theconcentration of the target chemical. The portion 70 is a photochemicalsensor which is less than ten microns in diameter. Again, the portion 70is small enough that it can pass through the membrane of a cell tomonitor the concentration and nature of chemicals within the cell.

The tip device 38 may have specific chemical sensitivities based uponthe properties of a dye matrix. A dye may be chemically activated by adifferent chemical compound which enables sensing of a specific chemicalproperty within a sample or a substance. The tip device 38 provides forenhanced sensitivity, selectivity, and stability when detecting aconcentration within a sample or substance. The tip portion or device 38may comprise a biologically active compound that is immobilized in anenvironment that is optically reactive. Additionally, the biologicallyactive compound can, in itself, be optically active. The sensor device10 interacts with the substance or sample to detect a specific chemicalor concentration within the substance.

With reference now to FIGS. 1, 2, and 4, the operation of the device 10will be explained in detail. In order to operate the device 10, theon/off switch 22 is pressed to initialize the device 10. Once powered,the device 10 may be inserted into a sample 80 to test for a particularconcentration of material within the sample 80. As shown in FIG. 4, thesample to be tested is a liquid 82 in a beaker 84. The tip portion 70 isinserted into the liquid 82 and at this point in time a beam of light,such as the beam of light 36, is transmitted into the liquid 82. Withthe tip portion 70 being in contact with the liquid 82, the liquid 82reacts chemically with the tip portion 70 and the color of the chemicalcomposing the sensor device 10 changes. As a result of this change, thecolor of the light reflected back into the tip portion 70 changes, suchas reflected beam of light 40, as compared to the beam of light 36. Theamount of this change can be quantified by the detector 42. Oncequantified signals are provided to the computer 44 which performs acalculation to determine the concentration of the particular chemicalbeing sensed and the result may be displayed in the display 20.

In further detail and again with reference to FIGS. 1, 2, and 4, oncethe device 10 is actuated by pressing the switch 22, the beam of light32 is sent from the light source 30 through the fiber optic 34 whichtransmits the beam of light 36 through the tip device 38 into the liquid82. The reflected beam of light 40 is reflected from the liquid 82 intothe tip device 38 to the detector 42. The detector 42 provides signalsto the computer 44 and the computer 44 determines the concentration of aparticular chemical within the liquid 82. This process may be termedphotochemical optical fiber sensing. Additionally, the chemicalproperties of the tip portion 70 of the sensor portion 14 may be changedto react with another chemical to detect some other chemical within asample. Further, instead of changing the chemical properties of the tipportion 70, it may only be necessary to change the light source 30 todetect some other chemical within a sample.

FIG. 5 illustrates another preferred embodiment of a sensor device 100which comprises a computer 102 which is connected to a light source 104by a wire 106. The light source 104 operates to provide light,represented by a light beam 108, to be projected at an optical device110. The optical device 110 may be a mirror which allows light, which isrepresented by a light beam 112, of a particular or predeterminedwavelength or frequency to pass through the device 110 to be directed ata fiber optic 114. The fiber optic 114 is connected to a connectordevice 116 and the fiber optic 114 passes light, such as light beam 118,through to the connector device 116. A beam of light 120 is transmittedfrom the connector device 116 to a sensor device 122. The sensor device122 is similar to the tip portion or device 38 which was shown in FIGS.2 and 3. Light, such as light beam 124, which may be reflected back froma sample (not shown) and through the sensor device 122, is directed tothe connector device 116. A light beam 126 is transmitted from theconnector device 116 to the fiber optic 114. The fiber optic 114 in turndirects a light beam 128 to the optical device 110. The optical device110 provides a light beam 130 of a particular or predeterminedwavelength or frequency to be directed at an optical detector device132. The optical detector 132 is connected by a wire 134 to the computer102 and provides signals to the computer 102. The computer 102 isoperatively programmed to use the signals provided from the opticaldetector 132 to calculate or determine the concentration of a substancewithin a sample.

Referring now to FIG. 6, the sensor device 100 is further showncomprising a pencil like body 150 which includes a central body portion152, an end cap 154, and a tip portion 156. The central body portion 152has a display 158 for displaying information such as glucoseconcentration. An ON/OFF switch 160 is also included in the central bodyportion 152 for controlling operation of the sensor device 100. Thesensor device 100 is illustrated having the tip portion 156 insertedinto a hand 162 of a patient. As has been previously discussed, the tipportion 156 is of an extremely small size and because of its small sizeinsertion of the tip portion 156 into the hand 162 will produce littleor no sensation. The other components of the sensor device 100, whichwere discussed with reference to FIG. 5, are all housed within thecentral body portion 152.

With particular reference now to FIGS. 5 and 6, in operation, the tipportion 156 of the sensor device 100 is inserted into a sample, such asthe hand 162, to detect the presence of a concentration of material,such as for example glucose. Once inserted into the hand 162, the ON/OFFswitch 160 is pressed by the user to initiate operation of the sensordevice 100. Actuation of the sensor device 100 causes the computer 102to operate the light source 104. The light beam 108 is sent to theoptical device 110 which causes the light beam 112 to be directed at thefiber optic 114 which in turn produces the light beam 118. The lightbeam 118 passes into the connector 116 and emerges as the light beam 120which is provided to the sensor device 122. With the sensor device 122being in contact with the hand 162, the sensor device 122 reactschemically with the hand 162 and the color of the chemical composing thesensor device 122 changes. The color of the light beam 124 which isreflected back into the sensor device 122 is then directed back into theconnector 116. The beam of light 126 is transmitted from the connector116 to the fiber optic 114 which in turn transmits the beam of light 128to the optical device 110. The optical device allows the light beam 130to be directed to the optical detector 134. The optical detector 134provides signals to the computer 102 which then determines theconcentration of glucose within the hand 162. The result may then bedisplayed in the display 158 of the sensor device 100. Once the resultis displayed, the user may remove the sensor device 100 from the hand162 and press the ON/OFF switch 160 to turn the sensor device 100 off.The sensor device 100 may be used again to determine the glucoseconcentration.

The sensor device 100 in actual construction is a small device and sizedand shaped to be pencil like. Because of its small size the sensordevice 100 may be used as a portable monitoring device. Additionally,the computer 102 may be a microprocessor chip, a customized integratedcircuit chip such as an ASIC chip, or any other device which is capableof processing electrical signals. Although not shown or made referenceto, a rechargeable battery or a replaceable battery may be used to powerthe sensor device 100. Further both devices 10 and 100 may haveincorporated therein a memory for storing information such as, forexample, a log of monitoring of the patient's glucose concentration,time of day of monitoring, and date of monitoring.

FIG. 7 depicts a block diagram of a third embodiment of a micro opticalfiber sensor device 200. The sensor device 200 comprises a computer 202which is connected to a light source 204 via a wire 206. The lightsource 204 projects a beam of light 208 into a section or portion of afiber optic 210. The fiber optic 210 is connected to a tip portion ordevice 212 and passes a beam of light 214 to the tip device 212. The tipportion or device 212 is similar in several respects to the tip device38 which was illustrated in FIGS. 2 and 3, however, the tip device 212is different in one respect. In fabricating the tip device 212, asdiscussed in U.S. Pat. Nos. 5,361,314 and 5,627,922, the tip device 212uses a multi-dye matrix tip which is photochemically attached to the tipdevice 212 to form a multi-functional sensor having an extremely smallsize. The multi-dye configuration allows for a multi-function sensor inwhich each dye may be chemically activated by a different chemicalcompound. This enables the tip device 212 to sense, detect, or monitormore than one chemical.

Since the tip device 212 is capable of monitoring two differentchemicals, two different light beams, such as light beams 216 and 218,will be reflected back from a sample and through the tip device 212.Each of the light beams 216 and 218 are directed to a detector 220 and222, respectively. Although not shown, it is possible to have an opticalcomponent, such as band pass filters, placed between the tip device 212and the detectors 220 and 222 to direct the light beams 216 and 218 to aspecific detector 220 or 222. The detector 220 is connected to thecomputer 202 by a wire 224 and electrical signals indicative of theconcentration of a particular chemical within a sample is provided tothe computer 202. Additionally, the detector 222 is connected to thecomputer 202 by another wire 226 and signals indicative of anotherchemical within the sample are provided to the computer 202. In thismanner, the computer 202 is programmed to receive the signals from thedetectors 220 and 222 and calculate or determine the concentrations ofthe two chemicals within the sample. Additionally, the sensor device 200may include a display (not shown) which would display the results of thecalculations. The sensor device 200 may also be provided with a powersupply 228 which is operatively connected by a wire 230 to the computer202. Although the device 200 is depicted to show the monitoring of atleast two different chemical compounds it is also contemplated that morethan two chemical compounds may be sensed, detected, or monitored by thedevice 200 by adding additional components, as has been taught andillustrated.

From all that has been said, it will be clear that there has thus beenshown and described herein a micro optical fiber sensor device whichfulfills the various objects and advantages sought therefor. It will beapparent to those skilled in the art, however, that many changes,modifications, variations, and other uses and applications of thesubject micro optical fiber sensor device are possible and contemplated.All changes, modifications, variations, and other uses and applicationswhich do not depart from the spirit and scope of the invention aredeemed to be covered by the invention, which is limited only by theclaims which follow.

What is claimed is:
 1. A sensor device for measuring a concentration ofa substance within a sample comprising:a sensor comprising an opticalfiber portion having a first end and a second end, the second end havinga tip portion attached thereto and an active material incorporatedwithin the tip portion, the tip portion adapted to be inserted into asample, the active material capable of interacting with a substancewithin a sample; a light source coupled to the first end of the sensorfor emitting a beam of light into and through the sensor and into asample, the emitted beam of light having a wavelength and the activematerial interacting with a substance within a sample to change thewavelength of the emitted beam of light to produce a reflected beam oflight and the sensor for transmitting the reflected beam of light out ofthe second end thereof; means for receiving the reflected beam of lightfrom the second end of the sensor for producing a signal indicative ofthe reflected beam of light; and a processor for receiving the signalindicative of the reflected beam of light and for processing the signalto determine the concentration of a substance within a sample.
 2. Thesensor device of claim 1 wherein the active material is preselected tointeract with a predetermined substance within a sample.
 3. The sensordevice of claim 1 wherein the reflected beam of light has a wavelengthwhich is different from the wavelength of the emitted beam of light. 4.The sensor device of claim 1 wherein the receiving means is an opticaldetector.
 5. The sensor device of claim 1 wherein the concentration tobe measured is glucose and the sample is a human.
 6. The sensor deviceof claim 1 further comprising a pencil shaped and sized body having atip portion, a central body, and an end cap.
 7. The sensor device ofclaim 1 wherein the tip portion comprises a biologically active compoundthat is immobilized in an environment that is optically reactive.
 8. Asensor device for measuring a concentration of a substance within asample comprising:a sensor comprising an optical fiber portion having afirst end and a second end, the second end having a tip portion attachedthereto and an active material incorporated within the tip portion, thetip portion adapted to be inserted into a sample, the active materialcapable of interacting with a substance within a sample; a light sourcefor emitting a beam of light of a preselected wavelength with the lightsource being coupled to an optical device capable of transmitting thebeam of light therethrough, the transmitted beam of light being directedinto the first end of the sensor, through the sensor, and out of thesecond end into a sample, the active material interacting with asubstance within a sample to change the wavelength of the transmittedbeam of light to produce a reflected beam of light and the sensor fortransmitting the reflected beam of light from the second end, throughthe sensor, and out of the first end thereof, the optical device beingfurther capable of reflecting the reflected beam of light; means forreceiving the reflected beam of light which is reflected by the opticaldevice for producing a signal indicative of the reflected beam of light;and a processor for receiving the signal indicative of the reflectedbeam of light and for processing the signal to determine theconcentration of a substance within a sample.
 9. The sensor device ofclaim 8 wherein the active material is preselected to interact with apredetermined substance within a sample.
 10. The sensor device of claim8 wherein the reflected beam of light has a wavelength which isdifferent from the wavelength of the transmitted beam of light.
 11. Thesensor device of claim 8 wherein the receiving means is an opticaldetector.
 12. The sensor device of claim 8 wherein the concentration tobe measured is glucose and the sample is a human.
 13. The sensor deviceof claim 8 further comprising a pencil shaped and sized body having atip portion, a central body, and an end cap.
 14. The sensor device ofclaim 8 wherein the tip portion comprises a biologically active compoundthat is immobilized in an environment that is optically reactive.
 15. Asensor device for measuring a concentration of a substance within asample comprising:a sensor comprising an optical fiber portion having afirst end and a second end, the second end having a tip portion attachedthereto and a first and a second active material incorporated within thetip portion, the tip portion adapted to be inserted into a sample, thefirst active material capable of interacting with a first substancewithin a sample and the second active material capable of interactingwith a second substance within a sample; a light source coupled to thefirst end of the sensor for emitting a beam of light into and throughthe sensor and into a sample, the emitted beam of light having awavelength and the first active material interacting with a firstsubstance within a sample to change the wavelength of the emitted beamof light to produce a first reflected beam of light, the second activematerial interacting with a second substance within a sample to changethe wavelength of the emitted beam of light to produce a secondreflected beam of light, and the sensor for transmitting the first andsecond reflected beams of light out of the second end thereof; means forreceiving the first and second reflected beams of light from the secondend of the sensor for producing a first signal indicative of the firstreflected beam of light and a second signal indicative of the secondreflected beam of light; and a processor for receiving the first andsecond signals and for processing the first and second signals todetermine the concentration of a first substance within a sample and theconcentration of a second substance with a sample.
 16. The sensor deviceof claim 15 wherein the receiving means comprises a first means forreceiving the first reflected beam of light and a second means forreceiving the second beam of light.
 17. The sensor device of claim 16wherein the first means for receiving is an optical detector and thesecond means for receiving is an optical detector.
 18. The sensor deviceof claim 15 wherein the first concentration to be measured is glucoseand the sample is a human.
 19. The sensor device of claim 15 furthercomprising a pencil shaped and sized body having a tip portion, acentral body, and an end cap.
 20. The sensor device of claim 15 whereinthe tip portion comprises a biologically active compound that isimmobilized in an environment that is optically reactive.